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GPS200 User's Manual
6: VDOP – This field is used to indicate the vertical dilution of precision with a resolution
-2
of 1x10
(unitless).
7: TDOP – This field is used to indicate the time dilution of precision with a resolution of
-2
1x10
(unitless).
PGN 129540 – GNSS Satellites in View
The GPS200 uses this PGN to provide the GNSS information on current satellites in view tagged
by sequence ID. Information includes PRN, elevation, azimuth, and SNR. Field 4 defines the
number of satellites. Fields 5 through 11 defines the satellite number and the information. Fields
5 through 11 are sequentially repeated for each satellite to be transmitted. The factory default
for periodic transmission rate is once per second. The transmission of this PGN can be disabled
or the transmission rate of this PGN can be changed (see PGN 126208 – NMEA Request Group
Function – Transmission Periodic Rate).
Field 1: SID – The sequence identifier field is used to tie related PGNs together. For example,
the GPS200 will transmit identical SIDs for 126992 (System Time), 128259 (Speed),
129026 (COG and SOG, Rapid Update), 129029 (GNSS Position Data), 129539
(GNSS DOPs), and 129540 (GNSS Satellites in View) to indicate that the readings
are linked together (i.e., the data from each PGN was taken at the same time although
they are reported at slightly different times).
2: Mode – This field always reads as 3 (Null), indicating that range residuals are used to
calculate position, and not calculated after the position.
3: Reserved (6 bits) – This field is reserved by NMEA; therefore, this field always
contains a value of 0x3F (the GPS200 sets all bits to a logic 1)
4: Number of SVs – This field is used to indicate the number of current satellites in view.
Fields 5-11 are repeated the number of times specified by this field's value.
5: PRN "1" – This field is used to indicate the Satellite ID Number of the satellite (1-
32=GPS, 33-64=SBAS, 65-96=GLONASS).
6: Elevation "1" – This field is used to indicate the Elevation of the satellite.
7: Azimuth "1" – This field is used to indicate the Azimuth of the satellite.
8: SNR "1" – This field is used to indicate the Signal to Noise Ratio (SNR) of the satellite.
9: Range Residuals "1" – The GPS200 always sets this field to a value of 0x7FFFFFFF
(data not available)
10: PRN Status "1" – This field is used to indicate the status of the first satellite in the list.
(0=Not Tracked, 1=Tracked but not used in solution, 2=Used in solution without
Differential corrections, 3=Differential Corrections available, 4=Tracked with
Differential Corrections, 5=used with Differential Corrections)
11: Reserved (4 bits) – This field is reserved by NMEA; therefore, this field always
contains a value of 0xF (the GPS200 sets all bits to a logic 1)
If Field 4 contains a value greater than one, then the group of fields 5 through 11 is repeated
until this group appears the number of times indicated by the value of Field 4.
GPS200 NMEA 2000
PGN 129538 – GNSS Control Status
The GPS200 uses this PGN to provide the GNSS common satellite receiver parameter status.
GPS200 sends this PGN only when requested by PGN 059904 (ISO Request).
Page A4 Appendix A – NMEA 2000
®
Non-Periodic Data Transmitted PGNs
®
Interfacing
Revision 1.3
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